Can you pick a winner?

This year's event began at 0800 GMT on Friday - 1700 of the 2600 postcards had been sold by 1400 GMT.

The cards cost �35 each but buyers do not discover the artist's identity until handing over their money.

There are currently 900 postcards left and the sale will continue until 6pm on Saturday 29 November.

"We have been quite surprised by the pace of this year's sale," said Sue Bradburn, a spokeswoman for the college.

Guessing game

Many of the cards by famous artists have been snapped up already, including an obscure sketch of a dog by Damian Hirst.

See a selection of the Secret postcards In pictures

The work was only recognised by the buyer because it included some writing coming out of the dog's mouth which matched a similar style in one of Hirst's books.

A postcard by Peter Blake took longer to sell and only was only bought at 2pm.

"People were probably expecting it to be a collage but it was a tiny pencil drawing of a toy soldier," said Ms Bradburn.

"There are still some really nice cards left," she added.

The famous sale is now in its 10th year and is expected to raise up to �100,000 to fund student art projects.